Jake Tapper Leaves ABC News for CNN

UPDATED: Tapper will become CNN's chief Washington correspondent and also host a weekday program beginning in 2013.

Jake Tapper is leaving ABC News for CNN where he'll become chief Washington correspondent and also host a weekday program on the network.

Tapper has been ABC's chief White House correspondent since the 2008 election and was assigned to the Obama campaign during the 2012 presidential election. He also this year published his third book; The Outpost: An Untold Story of American Valor.

ABC News president Ben Sherwood broke the news of Tapper's departure Thursday in an email to staffers announcing the promotion of Jonathan Karl as ABC's new chief White House correspondent.

"For years, Jake has set the pace for the White House press corps," wrote Sherwood. "A ferocious reporter – and now a best-selling author - he has built a reputation as one of the most prolific and multi-talented journalists on the beat, scoring scoop after scoop."

Additionally, Martha Raddatz, ABC's stand-out foreign affairs correspondent, will get a new title (chief global foreign affairs correspondent) and an expanded role at ABC News that will include primary substitute anchor for George Stephanopoulos on Sunday public affairs program This Week.

Rumors that Tapper was being courted by CNN first surfaced last spring. At that time Tapper said he "couldn't be happier" at ABC News. But he was passed over to succeed Stephanopoulos on This Week in favor of Christiane Amanpour, who left that chair in Dec. 2011, after barely a year in the job. Amanpour now splits her time between CNN - where she has spent the vast majority of her TV news career - and ABC News, where she is global affairs anchor.

Tapper was bypassed a second time for This Week when in the wake of Amanpour's departure it was announced that Stephanopoulos would get the chair back, pulling double-duty as host of Good Morning America. But Tapper contributed far more than mere minutes on the air. With deep connections in Washington, a prolific social media presence and a dogged pursuit of exclusive stories, he was also seen as among the truly independent journalists in an increasingly vituperative political climate.

Tapper continued to substitute for Stephanopoulos on This Week, though Raddatz, a national security and military expert, also has filled in. And she certainly distinguished herself in her handling of the vice presidential debate.

In a statement released by CNN, Tapper praised CNN's election coverage and also alluded to the impending leadership change at the network, which will see former NBC News executive Jeff Zucker coming aboard in January as president of CNN Worldwide.

“With CNN’s impeccable reporting during the elections and the exciting changes in the works for the network, this is a perfect time to join the CNN team,” said Tapper. “I am excited about the prospect of working with both the new leadership and some old friends and colleagues."